Average Speed and Force Question

Click For Summary
SUMMARY

The discussion focuses on calculating average speed and force in physics problems. The average speed of a car traveling 12 miles, with segments at 30 mph and 60 mph, is confirmed to be 40 mph using a weighted average formula. Additionally, the discussion presents a scenario involving constant acceleration, where the velocity changes from 8.0 m/s to 12.0 m/s over 3 seconds, and a problem requiring the calculation of force to move a crate with a mass of 32 kg and a static friction coefficient of 0.57 at an angle of 21 degrees. These problems highlight essential concepts in kinematics and dynamics.

PREREQUISITES
  • Understanding of average speed calculations
  • Knowledge of constant acceleration equations
  • Familiarity with static friction and force calculations
  • Basic grasp of vector components in physics
NEXT STEPS
  • Study the equations of motion for constant acceleration
  • Learn about the principles of static and kinetic friction
  • Explore vector decomposition in physics problems
  • Practice calculating average speed with varying velocities
USEFUL FOR

Students studying physics, educators teaching kinematics and dynamics, and anyone looking to improve their problem-solving skills in mechanics.

baltar
Messages
1
Reaction score
0
Hello everyone! I am really terrible at physics.
I genuinely tried doing them(looking for similar examples in the book and such), but am still stuck. If someone could point me in the right direction, I'd appreciate it. Thanks in advance!

1) A car is making a 12 mile trip. It travels the first 8.0 miles at 30mph and the last 4.0 miles at 60mph. What is the car's average speed for the entire trip?
I got 40mph. This is what I did 0.66666(30) + 0.33333(60) = 40mph.


2) A car is moving with constant acceleration. At t = 5.0 its velocity is 8.0m/s and t=8.0s its velocity is 12.0m/s. What is the distance traveled in that interval of time?

3) To move a large crate across a rough floor, you push on it with a force F at an angle of 21 degrees below the horizontal. Find the force necessary to start the crate moving, given that the mass of the crate is 32 kg and the coefficient of static friction between the crate and the floor is 0.57
 
Physics news on Phys.org
1. Use your knowledge of speeds and distance to compute the total time for the trip. Use that time and the total distance to get a average velocity.

2. and 3. Show us something of what you know about these situations.
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
1K
Replies
20
Views
2K
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 23 ·
Replies
23
Views
3K
Replies
11
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K